1. Field of the Invention
The invention is generally related to cleaning compositions and methods of using same. More particularly, the invention is related to cleaning compositions which are substantially free of volatile organic chemicals.
2. Brief Description of Related Technology
Cleaning compositions are well known. Most cleaning compositions contain at least one chemical substance which has broad application as a solvent.
Solvents make up a very broad and important segment of the chemical industry. Solvents are commonly used both in final products such as cleaners, polishes, pesticides, dyes, coatings, inks, and the like, and for the manufacturing of various products and chemical substances.
Important properties of solvents include the ability to dissolve other materials (or solvency), their purity and/or consistent composition, evaporation characteristics (including vapor pressure and non-volatile residue), adverse effects on humans (toxicity), adverse effects on the environment (biodegradability, ozone depletion), combustibility (flash point), availability, and cost. Because of their potential to damage both humans and the environment, solvents are the subject of many regulations.
Solvents are as diverse chemically as their applications and uses. The general term “solvent” implies an organic chemical substance, i.e., a molecule comprising carbon, hydrogen, nitrogen, oxygen, phosphorus, and/or sulfur.
When only carbon and hydrogen are present in solvent molecules, the solvents are classified as hydrocarbon solvents. Hydrocarbon solvents are typically derived from petroleum. Common petroleum hydrocarbon solvents include mineral spirits, kerosene, petroleum distillates, naphtha, Stoddard solvent, and aromatics. The foregoing hydrocarbon solvents are mixtures and have variable compositions, which depend upon the petroleum source and various manufacturing parameters. Other solvents consisting essentially of a single chemical component may also be derived from petroleum. Representative examples include toluene, benzene, hexanes, pentane, and the like.
When chemical elements in addition to carbon and hydrogen are introduced into the solvent molecules, other solvents are formed. For example, halogenated hydrocarbon solvents contain carbon, hydrogen, and chlorine and/or fluorine. As a group, halogenated solvents have many desirable properties such as high solvency, high evaporation rates, and high flash points. However, most of these substances are either banned from general use or are restricted in their use as solvents because of their detrimental effects on the environment and relatively high human toxicity.
Oxygenated solvents contain oxygen, carbon, and hydrogen. Oxygenated solvents are further divided into chemical classes such as alcohols, ketones, esters, and ethers. Each of these classes has specific properties which leads to it being more specialized in their application as solvents. Certain of these compounds exhibit varying degrees of relatively high human toxicity, however.
Additionally, many of the foregoing solvents are (or include) volatile organic compounds (VOC's), which are organic chemical compounds that have sufficiently high vapor pressures under normal conditions to significantly vaporize and enter the atmosphere. 40 C.F.R. §51.100(s) defines VOC to include “any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate, which participates in atmospheric photochemical reactions.” There are numerous exempted solvents, however. For example, various halogenated solvents are excluded. Additionally, 40 C.F.R. §59.203(e) provides that fragrances which are incorporated into a consumer product up to a combined level of two weight-percent are exempted from the VOC regulations. 40 C.F.R. §59.203(f) also exempts organic compounds having a vapor pressure of less than 0.1 millimeters of mercury at 20° C., organic compounds having more than 12 carbon atoms, if the vapor pressure is unknown, or organic compounds having a melting point higher than 20° C. which do not sublime (i.e., compounds which do not change directly from a solid into a gas without melting), if the vapor pressure is unknown.
In any event, VOC's participate in reactions that result in tropospheric ozone formation (and smog). Further, high concentrations of VOC's have been associated with various health problems. Because of their negative effects on the environment and human well being, such compounds are the subject of numerous regulations world wide. Of course, such regulations apply to paints, coating compositions, cleaning compositions, and other compositions comprising solvents.
Thus, there is a need for cleaning compositions which do not contain VOC's in appreciable quantities. Previous efforts to formulate cleaning compositions having relatively low VOC's have used solvents obtained from citrus fruits and soy beans. Although such products achieved low levels of VOC's relative to technologies existing at that time, further reductions in VOC levels are desired. It is a significant challenge, however, to reduce the level of VOC's in a cleaning composition while substantially retaining or even improving its cleansing power relative to prior art cleaning compositions containing higher levels of VOC's.